Environmental state debates focus on the governance and steering functions of politics. Concurrently, many states stand out as large global owners and investors in carbon industries. Via various investment vehicles, states control around half of all global oil and gas reserves as well as other carbon assets. We know very little, however, about where these states are invested; how they conduct their carbon investment; and what possibilities and constraints carbon-owning states have to decarbonise. Yet, these aspects - the geography, investment profiles and domestic state carbon capital dependence - are key to assess the possibilities and limitations of climate action states as carbon owners have. Based on new fine-grained firm-level data, we deliver conceptual and empirical insights into all three issues. Our intervention fills an important gap in our knowledge about the environmental state, while drawing the attention of researchers and policymakers to a blind spot, but also to transformation potentials of the carbon-owning state in the following decade.